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Osmotic stress inhibits leaf growth of Arabidopsis thaliana by enhancing ARF‐mediated auxin responses
Author(s) -
Kalve Shweta,
Sizani Bulelani L.,
Markakis Marios Nektarios,
Helsmoortel Céline,
Vandeweyer Geert,
Laukens Kris,
Sommen Manou,
Naulaerts Stefan,
Vissenberg Kris,
Prinsen Els,
Beemster Gerrit T. S.
Publication year - 2020
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/nph.16490
Subject(s) - auxin , arabidopsis thaliana , osmotic shock , mannitol , microbiology and biotechnology , cell division , transcriptome , biology , cell growth , arabidopsis , downregulation and upregulation , biochemistry , mutant , chemistry , cell , gene expression , gene
Summary We investigated the interaction between osmotic stress and auxin signaling in leaf growth regulation. Therefore, we grew Arabidopsis thaliana seedlings on agar media supplemented with mannitol to impose osmotic stress and 1‐naphthaleneacetic acid (NAA), a synthetic auxin. We performed kinematic analysis and flow‐cytometry to quantify the effects on cell division and expansion in the first leaf pair, determined the effects on auxin homeostasis and response ( DR5::β‐glucuronidase ), performed a next‐generation sequencing transcriptome analysis and investigated the response of auxin‐related mutants. Mannitol inhibited cell division and expansion. NAA increased the effect of mannitol on cell division, but ameliorated its effect on expansion. In proliferating cells, NAA and mannitol increased free IAA concentrations at the cost of conjugated IAA and stimulated DR5 promotor activity. Transcriptome analysis shows a large overlap between NAA and osmotic stress‐induced changes, including upregulation of auxin synthesis, conjugation, transport and TRANSPORT INHIBITOR RESPONSE1 ( TIR1 ) and AUXIN RESPONSE FACTOR ( ARF ) response genes, but downregulation of Aux/IAA response inhibitors. Consistently, arf7/19 double mutant lack the growth response to auxin and show a significantly reduced sensitivity to osmotic stress. Our results show that osmotic stress inhibits cell division during leaf growth of A. thaliana at least partly by inducing the auxin transcriptional response.